From: Markus <markus@...>
Date: 2004-09-29T15:20:59+09:00
Subject: Re: DRY ruby idiom


On Tue, 2004-09-28 at 21:30, Gavin Sinclair wrote:
> Steve Tuckner wrote:
> > a = "default"
> > a = foo.value if foo.value
> >
> > I just wanted to see if there was a simple way to avoid the double
> > foo.value that I was missing. Thanks for all your responses.
> 
> Ah, well _that's_ easy:
> 
>   a = foo.value || "default"
> 
> Gavin

     I was reading up this thread (I've been in meetings & working for
the past 8 hrs or so, and thus neglecting my duties as a netizen)
wondering if anyone had suggested this yet.  Will I be the one to post
it?  Will I?
    *sigh*

     I will not that (in the original poster's terms), this is

          var = val || var

which still repeats (but the computationally cheap var instead of the
presumably costly val).  There may be an idiom that avoids even that,
but I'll be darned if I know what it is.

       -- MarkusQ

P.S. In Icon (IIRC) you can write either

    var \= val

or 

    var /= val

one of which effectively does

    var ||= val

and the other 

    var = val || var

but the semantics of icon are sufficiently different from ruby to make
this only an approximate analogy.